JP2001098242A - Reactive hot-melt adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a reactive hot-melt adhesive composition which is excellent in workability on lamination and exhibits excellent resistances to heat and wet heat after curing. SOLUTION: This composition is tack-free at room temperature and contains a cationically polymerizable compound having, on average, at least one cationically polymerizable group represented by the formula per molecule, a polymeric film-forming agent comprising polyvinyl butyral, and a cationic photopolymerization initiator comprising an aromatic sulfonium salt having phosphorus hexafluoride as a counter anoin. In the formula, (m) and (n) are each 0, 1 or 2; and R1 to R4 are each independently H, methyl, ethyl, isopropyl, isoamyl or phenyl.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocurable reactive hot-melt adhesive composition which is applied by heat-melt coating and cures by irradiation of light. The present invention relates to a reactive hot melt adhesive composition which is slightly tacky, can be bonded at a relatively low temperature, and has excellent heat resistance and moisture heat resistance after curing.

[0002]

2. Description of the Related Art In various fields such as bookbinding, packaging, textile processing, furniture woodworking, light electricity and transportation, hot melt adhesives are used to bond various materials such as paper, fiber, wood, glass, plastic or metal. Widely used. When used, the hot melt adhesive is usually heated and melted at a temperature of about 70 to 200 ° C. in an applicator. The melted hot-melt adhesive is applied to the adherend in a molten state, or the hot-melt adhesive is applied to the adherend, a release film, etc., rolled up, or extruded by an extrusion coater. To form a film, and then adhere to each other by heating and pressing between different adherends or between adherends. The adherends are adhered to each other by cooling and solidifying the hot melt adhesive.

[0003] In the case of a hot melt adhesive, the time from the bonding of the adherends to the development of the adhesive strength is usually within one minute, which is very short. Therefore, the bonding operation can be performed in a very short time.

However, when the hot melt adhesive has tackiness at room temperature, air is entrapped between the hot melt adhesive and the adherend. Therefore, when heated in a later step, the entrapped air expands, causing a phenomenon called blistering, or when the adherend is thin, the appearance properties are greatly impaired by the blistering. was there.

[0005] JP-A-6-306304 discloses an epoxy / polyester hot melt composition. This hot melt composition is non-adhesive at room temperature, but because it uses polyester, when placed in an atmosphere under high temperature and high humidity, hydrolysis occurs,
Adhesive strength is significantly reduced.

Japanese Unexamined Patent Publication (Kokai) No. 4-185633 discloses a polyvinyl acetal-epoxy adhesive as a liquid adhesive at room temperature, which is not a hot melt adhesive. Therefore, this adhesive could not be superimposed on the adherend after being applied at room temperature. Also,
There is a disadvantage that the impact resistance is poor because the cured product is hard and brittle.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a reactive hot-melt adhesive having good workability, good adhesiveness, and excellent moisture-heat resistance and impact resistance of a cured product after curing. To provide an agent.

[0008]

The reactive hot melt adhesive composition according to the present invention comprises, on average, one cationically polymerizable reactive group having the structure of the following formula (1) per molecule.
Including a cationic polymerizable compound having the above, a polymer film-forming agent composed of polyvinyl butyral, and a photocationic polymerization initiator composed of an aromatic sulfonium salt having phosphorus hexafluoride as a counter anion, non-adhesive at room temperature It is characterized by the following.

[0009]

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(In the formula (1), m and n represent 0, 1 or 2, and R ¹ , R ² , R ³ and R ⁴ represent a methyl group, an ethyl group, an isopropyl group, an isoamyl group, It represents a phenyl group or a hydrogen atom, which may be the same or different.) As the cationically polymerizable compound, an epoxy compound is preferably used.

Further, as the cationically polymerizable compound,
More preferably, an epoxy resin obtained by copolymerizing a bisphenol A skeleton and ethylene oxide or propylene oxide is used.

The reactive hot melt adhesive composition according to the present invention may further contain a hydroxyl group-containing compound. Hereinafter, details of the present invention will be described.

(Cationically polymerizable compound) The cationically polymerizable compound used in the present invention is not particularly limited as long as it is an organic compound having an average of at least one cationically polymerizable group having the structure of the above formula (1). It may be any of a monomer, oligomer or polymer. Further, it may contain constituent atoms of organic compounds such as carbon, hydrogen, oxygen, nitrogen, sulfur and phosphorus, and the cationic polymerization reactive group may be present at the terminal of the molecular skeleton or may be present in the side chain. And it may be present in the molecular skeleton, and its structure and molecular weight are not particularly limited.

The cationically polymerizable compound may itself be a hot melt resin. Further, the cationically polymerizable compound may be in a liquid state at room temperature. In this case, the liquid cationically polymerizable compound and a solid thermoplastic resin can be mixed to provide a solid resin.

More specifically, examples of the cationic polymerizable compound include cyclic ether compounds (such as epoxy compounds, oxetane compounds and oxolane compounds), cyclic ester compounds, and vinyl ether compounds. Epoxy compounds are preferably used because of their excellent cationic polymerizability. In the present invention, two or more of the above cationically polymerizable compounds may be used in combination.

The "average" number of cationically polymerizable groups per molecule is determined by dividing the number of cationically polymerizable groups in the cationically polymerizable compound by the total number of existing cationically polymerizable compounds. Value.

As the cationic polymerizable compound, an epoxy resin obtained by copolymerizing a bisphenol A skeleton and ethylene oxide or propylene oxide is preferably used. Examples of such an epoxy resin include bisphenol A bis (propylene glycol glycidyl ether) ether, bisphenol A bis (triethylene glycol glycidyl ether) ether, and the like. Sex can be further enhanced.

(Polyvinyl butyral) The polyvinyl butyral used in the present invention is used as a polymer film forming agent. Polyvinyl butyral is obtained by reacting polyvinyl alcohol with butyraldehyde under an acid catalyst.

The degree of polymerization of the polyvinyl alcohol used to obtain polyvinyl butyral is preferably 2
Those having a saponification degree of 75 to 99.8 mol% are used. It is difficult to synthesize polyvinyl alcohol or modified polyvinyl alcohol having a degree of polymerization of less than 200,
If it exceeds 0, the viscosity of the aqueous solution may be too high, and uniform acetalization reaction may be difficult.

If the degree of saponification is less than 75 mol%, the solubility of polyvinyl alcohol in water may be insufficient, and it is difficult to achieve a degree of saponification exceeding 99.8 mol%.
Polyvinyl alcohol may be a modified polyvinyl alcohol, in which case the degree of modification is not particularly limited,
Preferably, the content of the monomer unit having a hydrophilic group is 10 mol% or less.

It is rarely necessary to modify the amount of the modified polyvinyl alcohol exceeding 10 mol%, and it is difficult to synthesize such a highly modified modified polyvinyl alcohol. The polyvinyl butyral can be considered as a copolymer of vinyl butyral, vinyl acetate, and vinyl alcohol. The number average molecular weight of the polyvinyl butyral is preferably 100
２００200,000, more preferably in the range of 200２００60000. Considering that it is used as a hot melt adhesive composition, if the number average molecular weight is too large, it may be difficult to melt and mix with other components, and if it is too small, the polymer film forming ability may be reduced. .

In the reactive hot melt adhesive composition according to the present invention, an aromatic sulfonium salt having phosphorus hexafluoride as a counter anion is preferably used as the cationic photopolymerization initiator.

A cationic polymerization initiator comprising an aromatic sulfonium salt having phosphorus hexafluoride as a counter anion as described above is disclosed in, for example, US Pat. No. 4,256,828.

Preferably, as the aromatic sulfonium salt compound having phosphorus hexafluoride as a counter anion, an aromatic sulfonium salt compound having a structure represented by the formula (2) or (3) is used. Such compounds are commercially available from Union Carbide Co., Ltd., trade name: Cyracure UVI-6990, Asahi Denka Kogyo KK, trade names: Optmer SP-150, SP151, and the like.

[0025]

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[0026]

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The above-mentioned cationic polymerization initiator does not produce cations under light outside the ultraviolet region. However, by using a known sensitizer such as an aromatic amine or a colored aromatic polycyclic hydrocarbon in combination, the cation polymerization initiator can produce a cation outside the myopic region. Also, cations are generated by light in the visible light region.

The effective compounding amount of the cationic polymerization initiator includes the type and intensity of the active energy ray, the type and compounding amount of the cationically polymerizable compound and the thermoplastic resin contained as necessary, the type of the cationic polymerization initiator, and the like. Although it is not particularly limited, it generally depends on the cationic polymerization initiator and 100 parts by weight of the cationically polymerizable compound.
0.1 to 10 parts by weight, preferably 0.1 to 10 parts by weight.
More preferably, it is part by weight.

If the amount of the cationic polymerization initiator is less than 0.01 part by weight, curing may not proceed sufficiently even when the reactive hot melt adhesive composition is irradiated with active energy rays. When the addition amount of the cationic polymerization initiator exceeds 10 parts by weight, the reactive hot melt adhesive composition irradiated with the active energy rays cures too fast, the pot life becomes too short, and the adherends become too short. May be difficult to attach.

(Hydroxyl Group-Containing Compound) The reactive hot melt adhesive composition according to the present invention may contain a hydroxyl group-containing compound, if necessary. The hydroxyl compound that can be used may be a liquid,
It may be solid. However, a hydroxyl compound having at least one, preferably two hydroxyl groups is used. The hydroxyl group may be present at the terminal of the compound or at the side chain of the polymer or copolymer.

Examples of the hydroxyl compound include, but are not limited to, alkylene glycol, polyhydroxylalkane, and polyoxyalkylene polyol. Also,
The hydroxyl compounds may be used alone or in combination of two or more.

Preferably, the hydroxyl group-containing compound has an aromatic ring and an ester bond in the molecule,
A hydroxyl group-containing compound having a primary hydroxyl group is used. Examples of such a hydroxyl group-containing compound include, for example, orthophthalic acid ester diethylene diol, propylene glycol and the like.

By adding a hydroxyl group-containing compound, the adhesion to an adherend can be increased, or the time available for bonding after irradiation with active energy rays until bonding can be adjusted.

When the above-mentioned hydroxyl group-containing compound is contained, the mixing ratio thereof is not particularly limited, but is preferably 1 to 100 parts by weight of the cationically polymerizable compound.
It is desirable to set the ratio to 50 parts by weight. If the amount is less than 1 part by weight, the above effects may not be obtained, and 50
If the amount exceeds the weight part, the heat resistance of the cured product may decrease.

(Other components that can be added) The reactive hot melt adhesive composition according to the present invention may further contain a thermoplastic resin, if necessary. The thermoplastic resin is not particularly limited, and for example, a tackifier resin, a polyolefin-based resin, a rubber-based resin, an acryl-based copolymer resin, and the like, which are conventionally widely used in hot melt adhesives, can be used. These thermoplastics are
Only one kind may be added, or two or more kinds may be added.

Further, the reactive hot melt adhesive composition according to the present invention may contain, if necessary, an adhesion improver (a silane coupling agent, a titanium coupling agent, etc.), a sensitizer, a dehydrating agent, an antiaging agent. Agents, stabilizers, plasticizers, waxes,
Components such as a filler, a flame retardant, a foaming agent, an antistatic agent, a fungicide, and a viscosity modifier may be added. However, the components that can be added are not limited to these. Further, two or more of these additive components may be used in combination. further,
These components may be added in advance to the components described above.

The method for producing the reactive hot-melt adhesive composition according to the present invention is not particularly limited, and any method may be employed as long as a predetermined amount of each component to be blended can be uniformly kneaded. Good, but it needs to be manufactured under moderate heating conditions that allow each component to melt. In addition, kneading of each component at the time of production may be performed without a solvent, for example, may be performed in an inert solvent such as aromatic hydrocarbon, acetate, ketone, etc., but is performed in an inert solvent. in case of,
After kneading, it is necessary to remove the inert solvent by reducing the pressure and / or heating. Specifically, one or two of a double helical ribbon bath or a gate bath, a paddle, a butterfly mixer, a planetary mixer, a three-roll, a kneader-type kneader, an extruder-type kneader-extruder, etc.
The components can be kneaded using more than one kind, but the device for kneading each component is not limited to these.

The mixing and dispersion of the components is preferably carried out at atmospheric pressure or, if necessary, at or above atmospheric pressure or at or below atmospheric pressure. Furthermore, the order of charging each component is not particularly limited, but in order to shorten the melting time or to prevent the resulting reactive hot melt adhesive composition from deteriorating, it is difficult to melt the components or the components that are difficult to melt. It is desirable to charge in order from the one that is hardly deteriorated by heat or mechanical shearing force. In particular, since the cationic polymerization initiator is easily decomposed or deteriorated by heat, it is preferable that the cationic polymerization initiator is charged last.

In the above-mentioned production, it is necessary to carry out the production in a state where an active energy ray effective for starting curing is blocked. The reactive hot melt adhesive composition according to the present invention is obtained as described above, but is non-tacky at room temperature. Non-tacky means not exhibiting tackiness,
Specifically, it means that the adhesive does not coalesce with anything other than the adhesive, such as the hand and the adherend, by touch pressure or hand pressure, and corresponds to the non-tacky property in this specification. I do.
Since the reactive hot melt adhesive composition according to the present invention is non-tacky at room temperature, it is easy to handle.

The method for storing the reactive hot melt adhesive composition according to the present invention is not particularly limited as long as it can block active energy rays effective for starting curing, but a preferred storage container is a pail can. For active energy rays effective to initiate curing, such as tin cans, drums, cartridges, release boxes, release trays, cardboard containers, paper bags, plastic bags (for example, composite films sandwiching aluminum foil) Various opaque containers may be mentioned, and are preferably used, but are not limited to these containers.The materials of these containers are not particularly limited as long as they can block active energy rays. Absent.

Further, the reactive hot melt adhesive composition according to the present invention may be used immediately after production without being stored, of course. In order to perform bonding using the reactive hot melt adhesive composition of the present invention described above, the hot melt adhesive composition is heated and melted, and is applied to one or both of the adherends in a molten state. Before or after lamination of the adherends, the coated reactive hot melt adhesive composition is irradiated with active energy rays, and the adherends are pressed against each other, or the hot melt adhesive is adhered to the adherend,
It is processed into a film by applying it to a release film, winding it up, or extruding it with an extrusion coating machine, irradiating it with active energy rays, and hot-pressing it between different adherends or between adherends. Or, after being sandwiched between different adherends or between adherends, irradiate with active energy rays, and in any case, when irradiating with active energy rays after bonding, either one of the adherends It is necessary to transmit active energy rays of a sufficient amount and wavelength to excite the cationic polymerization initiator.

The method of heating and melting the reactive hot melt adhesive composition for coating is not particularly limited. For example, the method may be performed by using a normal hot melt applicator or a hot melt coater. A method of applying the reactive hot-melt adhesive composition in a molten state to one or both of the adherends, and immersing one or both of the adherends in the reactive hot-melt adhesive composition in a heat-melted state Method, a method of spraying a hot-melt adhesive composition in a heat-melted state to one or both of adherends using a hot-melt air gun, a reactive hot-melt in a heat-melted state using an extruder or the like. A method in which the adhesive composition is extrusion-coated on one or both surfaces of the adherend, and the like, can be used, and any method is suitably employed.

Further, the reactive hot melt adhesive composition may be supplied to a coating device such as a hot melt applicator using a pail unloader or a cartridge dispenser, or may be a stick, a pellet, a slug,
It may be supplied to an application device such as a hot melt applicator in various shapes such as a block, a pillow, and a billet.

Further, regarding the heating and melting, the entire reactive hot melt adhesive composition may be heated and melted, or may be partially heated and melted only in the vicinity of the heating body.
The coating thickness of the reactive hot melt adhesive composition is not particularly limited as long as a desired adhesive strength can be obtained, and may be appropriately set according to the type of the adherend and the coating method. The thickness is preferably such that the energy rays can sufficiently reach the inside of the adhesive layer.

In any case of using any of the above-mentioned melt coating methods, after the reactive hot-melt adhesive composition is applied to the adherends, the coating time until the adherents are bonded to each other is set to be sufficiently long. When it is desired to perform the coating, it is preferable to perform the melt coating in a state in which the active energy rays effective for starting the curing are blocked, and to perform the irradiation with the active energy rays immediately before bonding.
The active energy ray irradiation may be performed when the coated reactive hot melt adhesive composition is in a molten state, or after the coated reactive hot melt adhesive composition is cooled and solidified. You may go.

The active energy ray for curing the reactive hot melt adhesive composition may be any one capable of generating a cation from the cationic polymerization initiator.
There is no particular limitation. The type of the active energy ray may be appropriately selected according to the type of the cationic polymerization initiator.
It is desirable to use an active energy ray containing light having a wavelength of 400 nm.

As the method of irradiating the active energy ray, the reactive hot melt adhesive composition may be directly irradiated, or the reactive hot melt adhesive may be passed through a transparent or translucent adherend or a protective film. The composition may be irradiated indirectly.

The irradiation source of the active energy ray is not particularly limited, but includes a carbon arc, a mercury vapor arc, a fluorescent lamp, an argon glow lamp, a halogen lamp, an incandescent lamp, a low-pressure mercury lamp, a high-pressure mercury lamp, Examples thereof include a high-pressure mercury lamp, a flash UV lamp, a deep UV lamp, a xenon lamp, a tungsten filament lamp, and sunlight, and one or more of these are suitably used.

The amount of irradiation of the active energy ray varies depending on the kind and amount of each component constituting the reactive hot melt adhesive composition, the coating thickness, the irradiation source of the active energy ray and the like. Although it cannot be determined, it is desirable that the irradiation amount at a wavelength effective for generating cations from the cationic polymerization initiator be in the range of 0.001 to 10 J / cm ² . However, since the reactive hot melt adhesive composition according to the present invention is cured with low irradiation energy,
A thickness of about 1000 mJ or more is sufficient.

The bonding and pressure bonding of the adherends may be performed when the reactive hot melt adhesive composition irradiated with the active energy ray is in a molten state, or the reactive hot melt adhesive composition irradiated with the active energy ray may be used. It may be performed after the hot melt adhesive composition is cooled and solidified. At this time, the reactive hot melt adhesive composition may be in a tacky state or a non-tacky state.

As a method for bonding and pressure bonding between adherends, for example, after applying a reactive hot melt adhesive composition to one adherend, the other adherend is laminated and then appropriately bonded. How to pressurize for the required time at pressure and temperature,
After applying the reactive hot melt adhesive composition to both adherends, a method of applying pressure at an appropriate pressure and temperature for a necessary time, and the like may be mentioned, but the method is not limited to these methods. In the above method, a hot press, a hot laminator, or the like may be used, or sufficient heating may be performed at the time of bonding and pressing to complete the curing of the reactive hot melt adhesive composition.

The reactive hot-melt adhesive composition according to the present invention can be sufficiently cured by irradiating the above-mentioned active energy ray under normal temperature and normal pressure. However, if it is desired to further shorten the curing time, heat the composition to an appropriate temperature. You may. In this case, as the heating method, the type and amount of each component constituting the reactive hot melt adhesive composition, the type and shape of the adherend, and the heating conditions, etc., cannot be uniquely determined, For example, a method of blowing hot air, a method of placing in a heated oven, a method of heating with a heater, and the like are mentioned, and one or more of these methods are suitably adopted, but are not limited to these methods. It is not something to be done.
The heating temperature for shortening the curing time is preferably lower than the temperature at which the reactive hot melt adhesive composition itself softens. Otherwise, the reactive hot-melt adhesive composition may be softened to cause a displacement of the bonded portion.

The adherend to which the reactive hot melt adhesive composition according to the present invention is applied is not particularly limited. For example, iron, aluminum, copper, lead, tin, zinc,
Metals or alloys such as nickel, magnesium, titanium, gold, silver and platinum or their painted bodies, various plastics or plastic mixtures, glass, concrete,
Various adherends composed of inorganic materials such as stones, mortars, ceramics, ceramics, and the like, cellulosic materials such as wood and paper, and a wide range of materials such as leather can be cited and can be suitably applied. In addition, the above various adherends may be adhered with adherends of the same material or adherents of different materials.

The shape of the adherend may be any shape such as a plate, a lump, a rod, a sheet, a film, a string, a fiber, a honeycomb, a tube, a particle, or the like. It may be adhered, or an adherend having a different shape may be adhered.

The reactive hot-melt adhesive composition according to the present invention can be used not only as a reactive hot-melt adhesive which is generally and widely used, but also as a structural adhesive or an elastic adhesive, or as a pressure-sensitive adhesive. It can also be suitably used as an agent, a sealing agent, a coating agent and the like. Specific uses of such a reactive hot melt adhesive composition include, for example, a door panel, a partition, a shutter, furniture, a blackboard, a white board, a core material and a surface material of a sandwich panel such as a panel for housing of office equipment. Adhesion; Adhesion of core materials such as door panels and ceiling materials as furniture, partitions, and automobile interior materials to surface materials; Polyolefin resin foam used as cushioning material, sound insulation material, heat insulation material, etc. in automobiles, building materials, electric products, etc. Adhesion of body and various base materials; Adhesion of lamp lens; Sponge abrasive, polishing cloth, scourer, foam mattress, fittings, packaging material, seating sheet, electric carpet, table, desk, system kitchen, television, speaker, etc. Manufacture; bonding of plywood and decorative board; application to tape bonding and flexible bonding; optical audio Bonding of video disks and magneto-optical disks, bonding of IC card substrates and decorative panels; bonding of car side moldings, body panel sealers, doors, peripherals of instrument panels, headlamps, tail lamps, windows, etc. Although a wide range of uses such as sealing are mentioned, it is needless to say that the present invention is not limited to these uses.

The reactive hot-melt adhesive composition according to the present invention can be used not only as a solid hot-melt adhesive composition but also as a support type or non-support type film or a non-adhesive tape at room temperature. It can also be used as an adhesive composition.

(Function) The reactive hot melt adhesive composition according to the present invention has the above-mentioned specific composition, and is melted and softened by heating. Can be applied to In addition, since the cation polymerization reactive group in the cation polymerizable compound reacts by irradiation with the active energy ray, it can be applied to an adherend at a relatively low temperature or formed into a film. Further, after the lamination, the above polyvinyl butyral is blended, so that both the lamination and the curing show excellent heat resistance and wet heat resistance.

Further, since it is non-adhesive at room temperature, it is excellent in workability.

[0059]

The present invention will be described in more detail by way of the following non-limiting examples. In the following, “parts” means “parts by weight” unless otherwise specified.

In the following Examples and Comparative Examples, reactive hot melt adhesive compositions were produced using the following raw materials. Cationic polymerizable compound 1 Oxetane manufactured by Toa Gosei Co., Ltd.
Product name: “XDO”.

Cationic polymerizable compound 2: diglycidyl ether of bisphenol A, manufactured by Yuka Shell Epoxy Co., Ltd.
Product name: “Epicoat 1001”. Polyvinyl butyral resin: Polyvinyl butyral having a number average molecular weight of 18,000, manufactured by Sekisui Chemical Co., Ltd., trade name:
"Eslec BX-1L".

Polyester resin: Polyester having a number average molecular weight of 25,000, manufactured by Toyobo Co., Ltd., trade name: "Vylon 2"
00 ”. Cationic polymerization initiator 1: manufactured by Union Carbide Co., Ltd., 6
Aromatic sulfonium salt having phosphorus fluoride as a counter anion, trade name: "CYRACURE UVI-6990".

Cationic polymerization initiator 2 manufactured by Asahi Denka Kogyo KK
Aromatic sulfonium salt having antimony hexafluoride as a counter anion, trade name: "OPTMER SP-170". Hydroxyl group-containing compound: Orthophthalic acid ester diethylene diol having a number average molecular weight of about 350, manufactured by Dainippon Ink and Chemicals, trade name: Spinodol RD3150
P ".

Example 1 (Production of Reactive Hot Melt Adhesive Composition) 40 parts of the above cationic polymerizable compound 1, 50 parts of a polyvinyl butyral resin, 10 parts of a hydroxyl group-containing compound,
One part of the cationic polymerization initiator 1 is put into a planetary mixer equipped with a jacket through which heated oil can be circulated, covered with aluminum foil, and then heated at 160 ° C. and 30 rpm at 6 rpm.
After mixing for 0 minutes, a reactive hot melt adhesive composition was obtained.

(Example 2 and Comparative Examples 1 to 3)
As shown in Table 2, a hot melt adhesive composition was obtained in the same manner as in Example 1 except that the composition was changed.

(Evaluation) For each of the adhesive compositions obtained in Examples 1 to 4 and Comparative Examples 1 and 2, the adhesive strength, the heat resistant adhesive strength and the adhesive strength after wet heat were evaluated in the following manner.

Adhesive strength: Using a roll coater set at a temperature of 150 ° C., the adhesive composition was applied to 25 × 125
It was applied to an SPCC dull steel plate of × 1.6 mm to a thickness of 200 μm. Next, a high-pressure mercury lamp “Jetlight JL” manufactured by ORK Mfg. Co., Ltd. was applied to the applied adhesive composition.
2300 "and a wavelength of 365 mm with an illuminance of 25 mW /
Ultraviolet rays were irradiated for 60 seconds to obtain cm ² . Thereafter, a 25 × 125 mm No. 9 cotton canvas is overlaid on the adhesive composition after a predetermined pot life (10 seconds or 1 minute), and the pressure is set to 120 ° C. for 2 minutes and 0.5 kg / cm ² . And pressed to obtain a peel test specimen. The peel test specimen was cured under an environment of 23 ° C. and a relative humidity of 67% for 7 days, and then subjected to a floating roller peel test at 25 ° C. in accordance with JIS K6854. Was defined as the adhesive strength.

Heat resistant adhesive strength: A peel test piece was prepared in the same manner as in the evaluation of adhesive strength. The peel test specimen was cured for 7 days in an environment of 23 ° C. and a relative humidity of 60%, and then subjected to a floating roller peel test at 80 ° C. according to JIS K6854. The adhesive strength was used.

A peel test specimen was prepared in the same manner as in the evaluation of the adhesive strength after wet heat. The peel test specimen was cured for 7 days in an environment of 23 ° C. and a relative humidity of 60%, and further left for 500 hours in an atmosphere of 85 ° C. and a relative humidity of 85%, and then at 80 ° C. in accordance with JIS K6854. Perform the floating roller peel test,
The maximum strength that led to peeling was defined as the adhesive strength after wet heat.

The results are shown in Table 1 below.

[0071]

[Table 1]

[0072]

The reactive hot melt adhesive composition according to the present invention is excellent in workability because it is non-tacky at room temperature. In addition, curing proceeds by irradiation with active energy rays, and the cured product is excellent in heat resistance.

Further, since polyvinyl butyral is contained as a polymer film forming agent, the cured product is also excellent in wet heat resistance. Further, the cationic photopolymerization initiator,
Since it is composed of an aromatic sulfonium salt having phosphorus hexafluoride as a counter anion, it has excellent stability at the time of heating, and therefore can easily and stably perform a melt coating operation.

Further, in the reactive hot melt adhesive composition according to the present invention, curing after irradiation with active energy rays is performed by a dark reaction. It can also be applied to the body. In addition, after curing, it develops various physical properties such as excellent adhesive strength and heat resistance, so it is a reactive hot melt for various industrial products such as automobiles, electrical products, electronics, communication materials, building materials, etc. It can be suitably used as an adhesive.

Further, since the reactive hot melt adhesive composition according to the present invention is of the active energy ray-curable type and not of the moisture-curable type, it is not necessary to strictly shut off moisture, and therefore, special production equipment is required. It is economical because there is no need to use packaging materials.

Therefore, it is possible to provide a reactive hot melt adhesive composition which can be suitably used under various environments. When an epoxy compound is used as the cationically polymerizable compound, curing proceeds rapidly because of excellent cationically polymerizable properties.

Further, when an epoxy resin obtained by copolymerizing a bisphenol A skeleton and ethylene oxide or propylene oxide is used as the cationically polymerizable compound, the cationically polymerizable property can be further improved, so that a higher heat resistance can be obtained. Sex can be obtained.

When the reactive hot melt adhesive composition according to the present invention is further provided with a hydroxyl group-containing compound, the addition of the hydroxyl group-containing compound enhances the adhesion to an adherend and increases the activity. It is possible to adjust the bondable time after energy beam irradiation until bonding.

When the above-mentioned hydroxyl group-containing compound has an aromatic ring and an ester bond in the molecule and has a primary hydroxyl group, the compound which is a poorly adherent PET
The adhesion to the film can be increased.

Claims (4)

[Claims] 1. A cationic polymerizable compound having an average of at least one cationically polymerizable reactive group having a structure of the following formula (1) per molecule: a polymer film-forming agent comprising polyvinyl butyral; A reactive hot melt adhesive composition comprising: a photocationic polymerization initiator comprising an aromatic sulfonium salt having phosphorus as a counter anion; and non-tacky at room temperature. Embedded image (In the formula (1), m and n represent 0, 1 or 2, and R ¹ , R ² , R ³ and R ⁴ represent a methyl group, an ethyl group, an isopropyl group, an isoamyl group, a phenyl group or Represents a hydrogen atom, which may be the same or different.) 2. The reactive hot melt adhesive composition according to claim 1, wherein the cationically polymerizable compound is an epoxy compound. 3. The reactive hot melt adhesive composition according to claim 1, wherein the cationically polymerizable compound is an epoxy resin obtained by copolymerizing a bisphenol A skeleton and ethylene oxide or propylene oxide. 4. The reactive hot melt adhesive composition according to claim 1, further comprising a hydroxyl group-containing compound.